Modeling And Numerical Simulation Of Ductile Fracture Behavior Of GH4169 Nickel-based Superalloy

The disks are critical components of the aeroengine,and once the engine disk is broken,it can be catastrophic.When the engine is designed,it is required to have sufficient reserve of the strength in burst speed.The burst of the disk under centrifugal force is essentially caused by the deformation and fracture of the disk material under the complex stress state.The reasonable modeling and prediction of plastic deformation and fracture process of disc material are of great significance to the development of analysis technology of the burst speed of the disk.In this paper,the theoretical modeling and numerical simulation of plastic deformation and ductile fracture of GH4169 nickel-base superalloy were carried out.The main research work and conclusions are as follows:The integral method of Bai-Wierzbizki plastic constitutive model was deduced,and its finite element user material subroutine has been compiled.The material parameters of B-W model of GH4169 alloy are optimized by the inversion method.Based on B-W model,the tensile response of GH4169 smooth and notched specimens was analyzed by finite element method.The results show that the plastic deformation of GH4169 alloy is related to stress triaxiality and Lode angle parameters.The plastic deformation behavior of GH4169 under complex stress state can be described and predicted effectively by the B-W model.Based on the B-W model,the distribution and evolution history of the equivalent plastic strain,the stress triaxiality and the Lode angle of GH4169 smooth and notched specimens were calculated by the finite element method.The MMC ductile fracture model material parameters of GH4169 were calibrated by the simulation results.Based on the MMC fracture model,the whole tensile fracture process of the smooth and notched specimens of GH4169 were simulated and studied.The analysis showed that: the fracture initiation position of specimen has close correlation of the hydrostatic pressure and Lode angle parameters.The ductile fracture behavior of GH4169 alloy can be described accurately by MMC model.The tensile test of the modified CT specimen with complex geometrical characteristics was designed and carried out.Based on the above established B-W plastic constitutive model and MMC fracture model,the tensile fracture process of the modified CT specimen was simulated and analyzed by finite element method.The results show that: The deformation response before fracture initiation and the position of fracture initiation,fracture mode and fracture path of the modified CT specimen could be predicted accurately by the B-W plastic constitutive model and MMC fracture model.